In mobile communication devices, bandpass filters serve for selecting desired frequency ranges for diverse signal paths. The desired frequency ranges can pass through the filter, while undesired frequency ranges are blocked.
US Patent Application Publication No. 2004/0130411 A1 discloses band-stop filters comprising electroacoustically active components.
U.S. Pat. No. 6,894,588 likewise discloses electroacoustic components, e.g., for improving adjacent channel selectivity.